A documentary style story about the students of class 4 who are forced to form a reserve unit against alien objects. Their class is turned into a shared sleeping area, they are taught to use firearms, and every day they go through a new set of exercise drills.

If they are expelled they cannot go to university, but if they stay they could die. Students feel the pressures of having to work in a strict military system, they fear the unexpected behavior of the enemy, and struggle to maintain friendships.